Gravity-actuated lock

ABSTRACT

A lock structure for an upwardly acting door of a truck van wherein a latch bolt and a manually engageable actuating member are pivotally mounted upon the door for movement around an axis substantially perpendicular to the plane of the door when it is in the closed position. The latch bolt has an elongated, arcuate hook portion adapted to extend below the lower edge of the door for engagement with a catch pin mounted in the truck bed. The latch bolt is urged by gravity to move more securely into the latched position, and first keeper means releasably holds the bolt in its latched position. Second keeper means releasably holds the bolt away from said latched position.

United States Patent Smith et al.

[ 1 Feb. 15, 1972 [54] GRAVITY-ACTUATED LOCK [72] Inventors: Vernon O. Smith, Ashley; John W. Binns,

Marion, both of Ohio [73] Assignee: Overhead Door Corporation, Marion,

Ohio

[22] Filed: Mar. 18,1970

[21 Appl.No.: 20,565

Related U.S. Application Data [63] Continuation-in-part of Ser. No. 690,605, Dec. 14,

1967, Pat. No. 3,510,162.

[56] References Cited UNITED STATESPATENTS 2,577,878 12/1951 DeCamp et al. ..292/2l0 X 3,347,580 10/1967 Whiting .292/ l 28 Primary Examiner-Richard E. Moore Attorney-Woodhams, Blanchard & Flynn [57] ABSTRACT A lock structure for an upwardly acting door of a truck van wherein a latch bolt and a manually engageable actuating member are pivotally mounted upon the door for movement around an axis substantially perpendicular to the plane of the door when it is in the closed position. The latch bolt has an elongated, arcuate hook portion adapted to extend below the lower edge of the door for engagement with a catch pin mounted in the truck bed. The latch bolt is urged by gravity to move more securely into the latched position, and first keeper means releasably holds the bolt in its latched position. Second keeper means releasably holds the bolt away from said latched position. I

10 Claims, 9 Drawing Figures PATENTEDFEB 15 m2 3.642.314

sum 2 or 2 Maw v54;

This application is a continuation-in-part of patent application Ser. No. 690,605, filed Dec. 14, 1967, now U.S. Pat. No. 3,510,162, issued May 5, 1970, and entitled Self-Adjusting Lock.

BACKGROUND OF THE INVENTION This invention relates in general to a lock structure for an upwardly acting truck door and, more specifically, to a type thereof which is capable of automatic self-adjustment to compensate for looseness in the door incident to wear or the tolerances of a conventional installation and which is incapable of accidental opening.

Persons familiar with the manufacture and maintenance of upwardly acting doors for truck vans, for example, have long been aware that the lock structures in such doors are subject to unusually rough treatment, even under substantially normal operating conditions. That is, truck doors and their lock structures are constantly exposed to the weather, they are often strained by the loads carried in the truck van or battered by external obstructions, and they are frequently subjected to excessive and destructive forces when the truck (or other vehicle) upon which they are mounted moves over uneven terrain. As a result, any looseness in the latching mechanism of the lock, which may be produced by normal wear, by improper initial installation or by lack of adjustment, is quickly magnified and accelerated to produce excessive and abnormal wear or even complete failure.

Where looseness exists between the latch bolt on the door and the catch in the truck bed, the result is a dancing door which is not only noisy and unsightly, but also aggravates the wear problem and usually accelerates lock failure. Moreover, if the door is counterbalanced and there is looseness-in the latching mechanism, the door will tend to vibrate or dance even when the vehicle is moved along substantially level terrain.

Many attempts have been made to avoid, or at least minimize, loose doors or loose door-latching mechanisms on trucks, and lock structures designed for this purpose are disclosed in said patent application, Ser. No. 690,605, filed Dec. 14, 1967, and in patent application, Ser. No. 669,481, filed Sept. 21, 1967, now U.S. Pat. No. 3,514,142, issued May 26, 1970 and entitled Truck Door Lock.

There are many circumstances where it is desirable to eliminate virtually all movement of the truck door when its lock is in the latched position. However, since it is at least economically impractical to construct a truck van and/or truck door of the upwardly acting type having no play, at least some looseness is present in the door when it is latched. Accordingly, the next best solution is to provide a latch mechanism which automatically adjusts itself to absorb or counteract any looseness which exists or subsequently develops in the door latch, as the result of movement of the vehicle or the door, while the door is in the latched position.

It was thought that automatic, self-adjustment of a loose latch mechanism required some form of resiliently flexible urging of the latch against the catch or of the door against the threshold. That is, without such resilient urging the vibrations of the truck would work the latch loose, regardless of how it was constructed, after which the accelerated wear could occur.

The latch mechanism in the aforesaid application, Ser. No. 690,605 does avoid the aggravated wear encountered by other types of latch mechanisms, particularly where some looseness exists in the door. However, existing lock structures, including those disclosed in said two applications, have certain limitations that have created problems avoided by the lock structure claimed in this application.

By way of example, the failure of springs used in many existing lock structures is a constant source of trouble. That is, a spring failure can make the lock inoperable or awkward to operate, and it can position the lock handle where it will jam against the header of the truck van opening. In addition, the

need for springs increases the initial cost and the cost of maintenance.

Accordingly, a primary object of this invention is the provision of an improved lock structure for an upwardly acting truck door wherein the latch mechanism of the lock structure is adapted to adjust automatically for, and thereby eliminate, looseness between the door and the truck bed resulting from normal wear, minor inaccuracies of installation, acceptable tolerances in parts and the relative movement of the various parts of a truck van associated with the door during normal operation of the truck, whereby the useful life of the lock structure and/or the door is extended.

A further object of this invention is the provision of a lock structure for a truck door in which the one-piece latch bolt has an elongated hook portion with a cammed surface which slideably engages the catch means in the truck bed by a relatively gradual wedging action, and in which the hook portion is continuously urged by gravity toward the locking position with said catch means when the lock mechanism is in its latched position.

A further object of the invention is the provision of a lock structure for a truck door wherein the latch means is engageable by handle means, and including a pair of keeper means for preventing accidental movement of the latch means away from its latched and unlatched positions.

A further object of this invention is the provision of a lock structure, as aforesaid, which can be readily and inexpensively installed by a person capable of installing existing lock structures for the same or similar purposes, which can be easily operated by any person capable of operating the truck upon which the lock structure is installed and which requires a minimum of adjustment when the lock structure is installed or during its subsequent use in order to overcome normal looseness which normally develops in upwardly acting truck doors.

Other objects and purposes of the invention will become apparent to persons familiar with lock structures for truck doors upon reading the following descriptive material and examining the accompanying drawings, in which:

FIG. 1 is a broken, fragmentary rear elevational view of a truck door and an adjacent portion of a truck bed including the lock structure embodying the invention.

FIG. 2 is a sectional view taken along the line Il-ll in FIG. 1.

FIG. 3 is a sectional view taken along the line III-Ill in FIG. 1.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. L

FIG. 5 is a sectional view taken along the lineV-V in FIG. I.

FIG. 6 is a broken sectional view taken along the line VI-Vl in FIG. 5.

FIG. 7 is a sectional view similar to FIG. 6 with parts thereof located in different operational positions.

FIG. 8 isa sectional view taken along the line VIII-VIII in FIG. 1.

FIG. 9 is a fragmentary view of said truck door showing the latched keeper in its released position.

For convenience in description, the terms upper, lower," left, right, front, rear and words of similar import will have reference to the lock structure of the invention and the parts of the truck door associated therewith as appearing in FIG. 1 which discloses the rear side of the lock structure. The terms inner, outer" and derivatives thereof will have reference to the geometric center of the lock structure of the invention and parts thereof or associated therewith.

SUMMARY OF THE INVENTION The objects and purposes of the invention, including those set forth above, have been met by providing a lock structure comprising catch means mounted in the bed of a truck or similar vehicle and a latch mechanism mounted upon the lower end of an upwardly acting door of the truck van and min-n In-M having a latch bolt including an elongated hook portion with a cammed inner surface engageable with the catch means. The latch bolt is pivotally mounted upon the door and is moved into the latched position by an actuating member which is held in its latching position by a first keeper. Gravity also opposes release of the latch bolt from its latched position. The actuating member is held away from its latching position by a second keeper.

DETAILED DESCRIPTION The lock structure of the invention, a preferred embodi ment of which is disclosed in FIG. 1, is comprised of a latch assembly 11 mounted upon the lower end of an upwardly acting door 12 for engagementwith a catch assembly 13 that is mounted in the bed 14 of an otherwise substantially conventional truck van, of which the door 12 is a part. In this particular embodiment, the door 12 is comprised of a plurality of horizontally hinged sections 16 which are disposed in a substantially vertical plane, when the door is closed, and in a substantially horizontal plane near the roof of the van when the door is open. A resiliently flexible weather seal (FIG. 2) is mounted on the lower edge of the door 12 and is engageable with the bed 14 in a conventional manner and for conventional purposes.

The catch assembly 13 (FIGS. 1, 5 and 6) is comprised ofan elongated, substantially rectangular casing 17 which is preferably fabricated from sheet or plate steel to form a top flange 18, a pair of sidewalls l9 and 20 (FIG. 5) and a pair of end walls 21 and 22 (FIG. 6). The sidewalls 19, 20 and the end walls 21, 22 define a catch chamber 23 which preferably opens upwardly to receive the latch bolt 47 and downwardly for drainage.

The top flange 18 (FIG. 2) preferably extends beyond both end walls 21, 22 and the rear sidewall 20 for engagement with the upper surface 26 of the bed 14 when the casing 17 is located within the opening 27 in the bed 14. The top flange 18 may be secured to the bed 14 by welding, by screws or any other convenient, conventional means.

The catch assembly 13 includes a catch pin 29, which is secured to and extends between the sidewalls 19 and 20 of the casing 17 about midway between the end walls 21 and 22.

The latch assembly 11 (FIG. 1) has amounting plate 31 which is secured to the rear surface of the door 12 adjacent the lower edge thereof by means of rivets 32. The axle 35 has an end portion 40 of reduced diameter which extends through an opening 41 in the mounting plate 31 and which is rigidly secured to plate 31 by means such as welding.

A manually operated lever or actuating member 33 (FIGS. 1, 6 and 7), which is rotatably supported on axle 35, is comprised of a housing 34 having a front wall 36 (FIG. 5) and a rear wall 37 which are interconnected by a peripheral wall 38 having a substantial opening 39 (FIG. 6). Said opening 39 is along the lower side of the housing 34 when the member 33 is in the latching position of FIG. 1. The front wall 36 and rear wall 37 of housing 34 have coaxial openings 42 and 45 through which the axle 35 extends to pivotally support the actuating member 33.

The actuating member 33 (FIG. 1) has an integral arm or handle 43 which projects from the housing 34 lengthwise thereof and substantially radially of the axle 35.

The latch bolt 47 (FIG. 6) has a shank 48, which is rotatably supported at its upper end upon the axle 35, and an elongated, arcuate hook 49 integral with the outer end of the shank 48 and having a slightly cammed inner surface 51. The portion of surface 51 adjacent shank 48 is nearer to axle 35 than is the portion of surface 51 adjacent the free end of the hook 49. The center of gravity of the latch bolt 48, when it is pivotally supported by axle 35, is in the hook 49 near the shank 48. Thus, gravity urges latch bolt 47 into its locked position of FIGS. 1 and 6. However, the edge 54 of the peripheral wall 38 limits movement of bolt 47 (FIG. 6) in a latching direction, and the edge 55 limits movement of the bolt 47 in the opposite direction relative to the lever 33.

The peripheral wall 38 includes a radially projecting, in tegral flange 58 adjacent the edge 55.

An, unlatched keeper 63 (FIGS. 6 and 7) is pivotally mounted upon a pivot pin 64 which is rigidly secured to the mounting plate 31 near the housing 34. The keeper 63 has a cam surface 67 on its upper end and a hook 68 near to and below the surface 67. The keeper 63 has a counterbalance 69 which extends in the opposite radial direction from the hook 68 relative to the pin 64. The counterbalance tends to move into a depending position which is obstructed bythe stop pin 71 secured to and projecting rearwardly from the mounting plate 31 below the pivot pin 64. That is, pin 71 positively limits clockwise rotation of keeper 63, as appearing in FIG. 1, so that the flange 58 will strike the cammed edge 67 above the hook 68 as the lever 33 is moved into its fully unlatched posi tion of FIG. 7. This engagement of keeper 63 pivots same clockwise in FIG. 7 so that the flange 58 can move below the hook 68 after which theforce of gravity, acting on the counterbalance 69, pivots the hook 68 into engagement with said flange 58 whereby the lever 33 is held in the unlatched position.

, The keeper 63 has two integral flanges 72 and 73, flange 72 extending away from the back side of hook 68 and flange 73 projecting laterally from the counterbalance 69. These flanges permit release of the keeper 63 from the flange 58 by the same hand which engages the lever 33 and thereafter moves same back to the latched position of FIG. 1.

The latched keeper 79 (FIGS. 1 and 6) is substantially flat and has an integral hub 81 near the upper edge thereof which is sleeved upon the pivot pin 82. The pivot pin 82 is rigidly secured to a support plate 83 which is riveted to the door 12 so that the pivot pin 82 is preferably (but not necessarily) located at a point spaced from the axle 35 slightly greater than the distance between said axle and the outer end of the arm 43. A downwardly and frontwardly projecting flange 84 is located at the outer end of the arm 43 and is positioned adjacent the lug 86 on the keeper 79 when said keeper is suspended from the pivot pin 82 and the lever 33 is in its latching position. The flange 84 has an opening 87 (FIG. 8) which is aligned with an opening 88 (FIG. 2) in lug 86, when the latch assembly 11 is in its latched position of FIG. 1, for reception of a conventional sealing band 89.

The keeper 79 has an arcuate edge 91 (FIG. 1) which extends over and is engageable by the upper edge 92 ofthe flange 84 when the keeper 79 is in its normal depending position. Accordingly, if the latch bolt should accidentally tend to work loose from the pin 29, due to irregular movements of the truck, for example, the arcuate edge 91 in the path of the projection 84 will positively prevent the actuating member 33 from rotating in a counterclockwise direction (FIG. 1) so that the disengagement of the bolt 47 from the pin 29 is positively prevented.

An integral flange 93 (FIG. 9) is provided on the support plate 83 rightwardly of the pivot pin 82 for engagement by the keeper 79 to limit rotational movement thereof. However, the flange 93 islocated so that the keeper 79 can be pivoted counterclockwise into a position where the edge 91 no longer obstructs the unlatching or upward movement of the handle 43.

The latched keeper 79 has a rearwardly projecting flange 94 (FIG. 1) which extends along the edge 91 and the lug 86. The flange 94 minimizes the opportunity for accidental disengagement thereof from the arm 43 by presenting a wide obstruction.

When the arm 43 is returned from its unlatched position of FIG. 7 to its latching position of FIG. 1, the flange 84 strikes the upper edge 95 of the keeper 79 on the leftward side of the pivot pin 82 and thereby pivots the keeper 79 in a counterclockwise direction (FIG. 9) until the flange 84 reaches a posi tion below the arcuate edge 91 whereupon the keeper 79 will swing under the force of gravity into its FIG. 1 position and thereby block upward movement of the flange 84, hence the arm 43.

The length and radius of the arcuate edge 91 are preferably selected so that the edge 91 cannot be moved away from a Ina- position obstructing the upward movement of the projection 84 when a conventional sealing band 89 is threaded through the aligned openings 87 and 88 in flange 84 and lug 86. However, there are occasions when an oversized sealing band 89A is furnished and such might permit sufficient movement of the keeper 79 to raise the handle 43 and disengage the bolt 47 from the pin 29 without breaking the seal. To avoid this, the keeper 79 has a second downwardly projecting and integral lug 96 which is spaced from the lug 86. Lug 96 has an opening 97 (FIG. 2) through which the oversized band 89A (FIG. 1) extends.

The mounting plate 83 has an integral, rigid hook 98 which extends rearwardly and then upwardly from the lower edge thereof adjacent the inner side of the flange 84. The outer end of the handle 43 has an enlargement 101 containing a downwardly opening recess 102 (FIGS. 6 and 8) into which the hook 98 is slideably received when the lever 33 is in its latched position. This arrangement provides an additional precaution against accidental movement of the lever 33 out of a position where it holds the bolt 47 in position of engagement with the pin 19.

OPERATION The operation of the door lock structure described above will be apparent from such description to a person of ordinary skill in the manufacture of truck door locks. However, primarily for the purpose of convenience, the lock operation will now be summarized.

When it becomes desirable to latch the assembly 11, the handle 43 (FIG. 1) is rotated in a clockwise direction until the hook 49 of the latch bolt 47 engages the pin 29 in the catch assembly 13. Ordinarily, the latching movement of the handle 43 will commence from its unlatched position of FIG. 7 in which it is releasably held by the keeper 63. Also, the seal (FIG. 5) will normally be close to or in engagement with the bed 14 of the truck van. Thus, before such latching movement can occur, it is necessary for the operator to pivot the keeper 63 from its FIG. 7 position into its FIG. 6 position so that the flange 58 can move upwardly past the hook 68. The pivoting of keeper 63, which is opposed by the action of gravity upon the counterbalance 69, can be accomplished by engaging the keeper 63 with the thumb or finger of the hand grasping the handle 43.

Since the upper surface 51 of hook 49 is cammed, the free end thereof passes easily beneath the pin 29 until the surface 51 firmly engages said pin. The latch assembly 11 and catch assembly 13 are preferably installed on the truck so that the pin 29 is snugly engaged by the midportion of the cammed surface 51 when the hook 98 extends into the recess 102 in the enlargement 101 at the end of handle 43, as shown in FIG. 6, to prevent lateral movement of the handle 43.

As the handle 43 is moved into the latched position of FIG. 6, engagement of the hook shank 48 by the edge 55 forces a clockwise movement of the bolt 47, thereby ensuring a firm engagement between the surface 51 and the pin 29. Thereafter, should the door 12 be jarred or shifted downwardly, as during operation of the truck, gravity urges the latch bolt 47 in a clockwise direction thereby taking up any slack that may develop between surface 51 and pin 29.

As the latch assembly 11 moves into its latched position, the flange 84 engages the upper surface 95 of the latched keeper 79 and pivots same in a counterclockwise direction into its position of FIG. 9 so that the flange 84 can move past the keeper 79 into the latched position of FIG. 6 beneath the arcuate edge 91 ofthe keeper 79.

The engagement of the hook 98 with the enlargement 101 minimizes the rattling noise and further wear resulting from a loose handle 43. In fact, said hook and enlargement prevent an unauthorized, nondestructive release of the latch which could occur if the arm 43 becomes sufficiently loose to move upwardly past the rearward side of the keeper 79.

When it becomes desirable to disengage the latch bolt 47 from the catch assembly 13, the latched keeper 79 (FIG. 1) is rotated in a counterclockwise direction, after the seal 89 is released, into the position of FIG. 9. Counterclockwise rotation of the actuating member 33 causes the hook 49 of latch bolt 47 to move from beneath the pin 29. If, as usual, the hook 49 is somewhat wedged beneath the pin 29, it is broken loose by effecting short counterclockwise movements of the handle 43 whereby the edge 54 (FIG. 6) hammers against the shank 48.

After the bolt 47 is released from the pin 29, continued counterclockwise movement of the handle 43 brings the flange 58 into engagement with the cam surface 67 on top of the hook 68 whereby said hook is pivoted into this FIG. 6 position. The flange 58 can now move below the hook which returns to its FIG. 7 position under the force of gravity and releasably holds the handle 43 in its unlatched or inoperative position. When the handle 43 reaches its substantially horizontal and unlatched position, it will not interfere with the opening or closing movement of the door.

It will be seen from the foregoing that the lever 33 is held in its latched or operating position and in its unlatched or inoperative position without the aid of springs. Moreover, the lever can be easily released and moved away from these positions without difficulty. The catch pin 29 can be loosely encircled by a sleeve as disclosed in said pending application, Ser. No. 690,605.

Although a particular preferred embodiment of the invention has been disclosed above for illustrative purposes, it will be understood that variations or modifications of such disclosure are fully contemplated.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an upwardly acting door for the van of a truck having a bed, a door lock structure, comprising:

an actuating member pivotally mounted upon the door near the lower edge thereof for movement around a pivot axis parallel with said bed when said lower edge is adjacent thereto;

a latch bolt pivotally supported upon said door for movement around said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door, the center of gravity of said bolt being near said shank, and the radially inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface;

catch means mounted to said bed below and substantially parallel with said pivot axis, said catch means being arranged for snug engagement by said surface of said hook means while said center of gravity is spaced from and disposed between said shank and a line passing through said pivot axis and said catch means whereby the lower edge of said door is held closely adjacent said bed;

first keeper means pivotally mounted upon said door and releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door, wherein removal of said hook means from a position beneath said catch means is positively prevented; and

second keeper means pivotally mounted upon said door and releasably engageable with said actuating member to hold same in an inoperative position substantially on the opposite side of said axis from said operative position thereof, wherein said lock structure is incapable of interference with the movement of said door.

2. A lock structure according to claim 1, wherein said actuating member includes flange means;

wherein said second keeper means has hook means engageable with said flange means for holding said actuating member in said inoperative position; and

"II/171 nan;

wherein said second keeper means has counterbalance means urged by gravity to holdsaid hook means in engagement with said flange means.

3. A lock structure according to claim 1, wherein:

said actuating member has an elongated, manually engageable arm extending substantially radially away from said pivot axis, said arm having a flange projecting therefrom toward said door; and

wherein said first keeper means has an arcuate edge concentric with the pivot axis thereof and arranged for engagement by said flange when said actuating member is in said operative position for positively and releasably preventing movement of said actuating member out of said operative position.

4. A lock structure according to claim 3, wherein said actuating member includes flange means;

wherein said second keeper means has hook means engageable with said flange means for holding said actuating member in said inoperative position; and

wherein said second keeper means has counterbalance means urged by gravity to hold said hook means in engagement with said flange means.

5. A structure according to claim 2, including a mounting plate rigidly secured to said door and shaft means pivotally supporting said actuating member and said latch bolt, said shaft means being rigidly secured to said mounting plate;

pin means rigidly secured to said mounting plate and engageable by said second keeper means for positively limiting pivotal movement thereof; and

wherein said hook means of said second keeper means has a cammed surface on its upper edge engageable by said flange means whereby said hook means of said second keeper means is moved into the position of engagement with said flange means as said actuating member approaches said inoperative position.

6. A structure according to claim 1, wherein said catch means comprises a catch pin rigidly secured to said bed below said upper surface thereof, and said inner surface of said hook means defining part of an involute curve.

7. A structure according to claim 1, including a resiliently flexible sealing element secured along the said lower edge of said door, said sealing element being resiliently compressible against said bed, whereby relative movement between said door and said bed will tend to compress said sealing element and subsequently move said inner surface of said hook means in a latching direction along said catch means, due to the urging of gravity.

8. A lock structure according to claim 1, including upwardly projecting element means on said door adjacent a lower edge of said actuating member when said member is in said operative position, said element means having a vertical opening; and

means defining a downwardly opening recess in said actuating member adapted to snugly and slideably receive said element means when said member is in said operative position.

9. In an upwardly acting door for the van ofa truck having a bed, a door lock structure, comprising:

an actuating member pivotally mounted on the door near the lower edge thereof for movement about a pivot axis parallel with said bed when said lower edge is adjacent thereto, said actuating member having integral flange means extending substantially radially from said pivot axis;

a latch bolt pivotally supported upon said door for movement about said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door, the center of gravity of said bolt being near said shank, and the radially inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface; catch means mounted to said bed and having an edge releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door, wherein removal of said hook means from a position beneath said catch'means is positively prevented; and

second keeper means pivotally mounted upon said door and having hook means releasably engageable with said flange means on said, actuating member to hold same in an inoperative position substantially on the opposite side of said axis from said operative position thereof, wherein said lock structure is incapable of interference with the movement of said door and said bolt is incapable of engagement with said catch means.

10. In an upwardly acting door for the van of a truck having a bed, a door lock structure comprising:

an actuating member pivotally mounted upon the door near the lower edge thereof for movement around a pivot axis parallel with said bed when said lower edge is adjacent thereto;

a latch bolt pivotally supported upon said door for movement around said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door,

the center of gravity of said bolt being near said shank,

and the radially inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface;

catch means mounted to said bed below said pivot axis, said catch means being arranged for snug engagement by said surface of said hook means while said center of gravity is spaced from and disposed between said shank and a line passing through said pivot axis and said catch means whereby the lower edge of said door is held closely adjacent said bed;

keeper means movably mounted upon said door and releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door wherein removal of said hook means from a position beneath said catch means is positively prevented; and

means mounted upon said door and engageable with said actuating member to support same in an inoperative position substantially on the opposite side of said axis from said operative position. 

1. In an upwardly acting door for the van of a truck having a bed, a door lock structure, comprising: an actuating member pivotally mounted upon the door near the lower edge thereof for movement around a pivot axis parallel with said bed when said lower edge is adjacent thereto; a latch bolt pivotally supported upon said door for movement around said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door, the center of gravity of said bolt being near said shank, and the radiaLly inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface; catch means mounted to said bed below and substantially parallel with said pivot axis, said catch means being arranged for snug engagement by said surface of said hook means while said center of gravity is spaced from and disposed between said shank and a line passing through said pivot axis and said catch means whereby the lower edge of said door is held closely adjacent said bed; first keeper means pivotally mounted upon said door and releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door, wherein removal of said hook means from a position beneath said catch means is positively prevented; and second keeper means pivotally mounted upon said door and releasably engageable with said actuating member to hold same in an inoperative position substantially on the opposite side of said axis from said operative position thereof, wherein said lock structure is incapable of interference with the movement of said door.
 2. A lock structure according to claim 1, wherein said actuating member includes flange means; wherein said second keeper means has hook means engageable with said flange means for holding said actuating member in said inoperative position; and wherein said second keeper means has counterbalance means urged by gravity to hold said hook means in engagement with said flange means.
 3. A lock structure according to claim 1, wherein: said actuating member has an elongated, manually engageable arm extending substantially radially away from said pivot axis, said arm having a flange projecting therefrom toward said door; and wherein said first keeper means has an arcuate edge concentric with the pivot axis thereof and arranged for engagement by said flange when said actuating member is in said operative position for positively and releasably preventing movement of said actuating member out of said operative position.
 4. A lock structure according to claim 3, wherein said actuating member includes flange means; wherein said second keeper means has hook means engageable with said flange means for holding said actuating member in said inoperative position; and wherein said second keeper means has counterbalance means urged by gravity to hold said hook means in engagement with said flange means.
 5. A structure according to claim 2, including a mounting plate rigidly secured to said door and shaft means pivotally supporting said actuating member and said latch bolt, said shaft means being rigidly secured to said mounting plate; pin means rigidly secured to said mounting plate and engageable by said second keeper means for positively limiting pivotal movement thereof; and wherein said hook means of said second keeper means has a cammed surface on its upper edge engageable by said flange means whereby said hook means of said second keeper means is moved into the position of engagement with said flange means as said actuating member approaches said inoperative position.
 6. A structure according to claim 1, wherein said catch means comprises a catch pin rigidly secured to said bed below said upper surface thereof, and said inner surface of said hook means defining part of an involute curve.
 7. A structure according to claim 1, including a resiliently flexible sealing element secured along the said lower edge of said door, said sealing element being resiliently compressible against said bed, whereby relative movement between said door and said bed will tend to compress said sealing element and subsequently move said inner surface of said hook means in a latching direction along said catch means, due to the urging of gravity.
 8. A lock structure according to claim 1, including upwardly projecting element means on said door adjacent a lower edge of said actuating Member when said member is in said operative position, said element means having a vertical opening; and means defining a downwardly opening recess in said actuating member adapted to snugly and slideably receive said element means when said member is in said operative position.
 9. In an upwardly acting door for the van of a truck having a bed, a door lock structure, comprising: an actuating member pivotally mounted on the door near the lower edge thereof for movement about a pivot axis parallel with said bed when said lower edge is adjacent thereto, said actuating member having integral flange means extending substantially radially from said pivot axis; a latch bolt pivotally supported upon said door for movement about said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door, the center of gravity of said bolt being near said shank, and the radially inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface; catch means mounted to said bed and having an edge located at a position below said pivot axis for snug engagement by said radially inner surface of said hook means while said center of gravity is spaced from and disposed between said shank and a line passing through said pivot axis and said edge of said catch means, whereby the lower edge of said door is held closely adjacent said bed; first keeper means pivotally mounted upon said door and releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door, wherein removal of said hook means from a position beneath said catch means is positively prevented; and second keeper means pivotally mounted upon said door and having hook means releasably engageable with said flange means on said actuating member to hold same in an inoperative position substantially on the opposite side of said axis from said operative position thereof, wherein said lock structure is incapable of interference with the movement of said door and said bolt is incapable of engagement with said catch means.
 10. In an upwardly acting door for the van of a truck having a bed, a door lock structure comprising: an actuating member pivotally mounted upon the door near the lower edge thereof for movement around a pivot axis parallel with said bed when said lower edge is adjacent thereto; a latch bolt pivotally supported upon said door for movement around said axis and with respect to said actuating member, said latch bolt having a shank and elongated arcuate hook means extending sidewardly from said shank and adapted to extend below said lower edge of said door, the center of gravity of said bolt being near said shank, and the radially inner surface of said hook means near the free end thereof being spaced radially from said axis a distance slightly greater than the opposite end of said surface; catch means mounted to said bed below said pivot axis, said catch means being arranged for snug engagement by said surface of said hook means while said center of gravity is spaced from and disposed between said shank and a line passing through said pivot axis and said catch means whereby the lower edge of said door is held closely adjacent said bed; keeper means movably mounted upon said door and releasably engageable with said actuating member to hold said actuating member in an operative position with respect to said door wherein removal of said hook means from a position beneath said catch means is positively prevented; and means mounted upon said door and engageable with said actuating member to support same in an inoperative position substantially on the opposite side of said axis from said operative position. 